Who would you cast in a Half-Life movie?

If a movie based on Valve's Half-Life were to be greelit, who would you cast in it? Who would direct it? Who would play Gordon, G-Man, Alyx, Eli, and Barney? Would it be live-action with cgi or 3d animation? What parts of the Half-Life timeline would you cover in a feature?

Preferably someone who's really hot or really weird-looking, because god knows the first half hour of that movie would be fucking boring dialogue-wise and visually, if it's inspired by the first half of the game. As Yahtzee so nicely put it, "Ooh look at the crazy shit we've done with the Quake engine."